Thalamic Lacunar Infarcts and Ipsilateral Eye Manifestations
Yes, acute thalamic lacunar infarcts can cause eye problems on the same side (ipsilateral) as the infarct, particularly when the infarct involves the paramedian or anteromedial thalamic territory.
Specific Ipsilateral Eye Manifestations
The most common ipsilateral eye findings with thalamic infarction include:
- Ptosis (drooping eyelid) occurs ipsilaterally, particularly with anteromedial thalamic infarcts 1
- Miosis (pupil constriction) can present as an isolated finding on the same side as the infarct 2
- Third nerve palsy affecting the ipsilateral eye has been documented in thalamic infarction cases 2
Contralateral Eye Findings Are More Common
However, it's critical to understand that contralateral (opposite side) eye findings are actually more frequent than ipsilateral manifestations:
- Skew deviation with invariable hypotropia of the contralesional (opposite) eye occurs in approximately 5% of thalamic infarct patients 2
- Vertical gaze palsy (affecting both eyes but more prominent contralaterally) is the most common oculomotor finding, occurring in approximately 6% of cases 2
- Pseudoabducens palsy affecting the contralateral eye 2
Location Matters: Paramedian Territory
Paramedian thalamic infarcts are responsible for 84.8% of all neuro-ophthalmologic manifestations in thalamic stroke 2. This is because:
- Paramedian infarcts often extend into the rostral midbrain tegmentum, affecting the interstitial nucleus of Cajal (INC) 3
- This extension into midbrain structures, rather than the thalamic tissue itself, causes most of the oculomotor deficits 3
- When the rostral midbrain tegmentum is involved, complete ocular tilt reaction can occur with contraversive (opposite side) head tilt, skew deviation, ocular torsion, and subjective visual vertical tilt 3
Visual Field Defects
Visual field defects occur in approximately 2% of thalamic infarct patients and can affect the visual field corresponding to the side of the lesion 2. These are typically homonymous hemianopsias affecting the contralateral visual field.
Prognosis and Recovery
Most oculomotor abnormalities from thalamic infarction resolve spontaneously within a few months 2. However:
- Approximately 18% of patients develop permanent oculomotor deficits 2
- Poor prognostic indicators include: no improvement within 3 months, combined upgaze and downgaze palsy, and involvement of the paramedian tegmentum of the rostral midbrain 2
- Deficits persisting beyond 3 months may remain permanent for years 2
Critical Clinical Pitfall
Do not confuse thalamic stroke eye findings with retinal artery occlusion. While both can present with acute visual symptoms, retinal artery occlusions (CRAO/BRAO) require immediate emergency department referral within 24 hours due to high concurrent stroke risk 4, 5. Thalamic infarcts present with oculomotor deficits (eye movement problems, ptosis, pupil changes) rather than vision loss from retinal ischemia.
Acute Symptoms to Monitor
Beyond eye findings, acute thalamic lacunar infarcts commonly present with 6:
- Disorders of consciousness
- Hypersomnia
- Vertical gaze paresis
- Amnesic syndrome of variable duration